Image element antennas and the operation thereof are described in detail in a paper entitled "Partially Reflecting Sheet Arrays", IRE Transactions On Antennas and Propagation, October 1956, pages 666 through 671. Also, an image element antenna array is described in U.S. Pat. No. 3,990,078, entitled "Image Element Antenna Array For a Monopulse Tracking System For a Missile", issued Nov. 2, 1976 and assigned to the same assignee.
The above described patent discloses a multi-element antenna array and coupling apparatus for connecting power to and taking power from the array. However, a single frequency antenna is disclosed and, in many applications it is desirable to reuse the same frequency or to utilize a different frequency. Generally such frequency reuse is severely limited or prohibited by high mutual coupling and pattern degradation.